Heater system



Serif. 30, 1947 s4. E. `HEYMANN 2,428,078

HEATERA SYSTEM Filed April 2. 1943 2 sheets-sheet 1 NQ. Mmmm Sept. 30, y1947 s. E. HEYMANN 2,428,078

` HEATERA ss'ma Filed April 2, 194s 2 sheets-sheet 2 Patented sept. so, `1947 HEATER SYSTEM Seymour E. Heymann, Chicago, Ill., assigner to Stewart-Warner Corporation, Chicago. lll., a corporation of Virginia Application April 2, 1943, Serial No. 481,554

2 Claims. (Cl. 237-2)- My invention relates to heater systems which are particularly designed for, but not limited to, use in aircraft.

An object of myY invention is to provide a new and improved heater system for controllingthe heat output of an internal combustion type of heater.

Another object of my invention is to provide a new and improved heater system which is simple, emcient, inexpensive to install and which is adapted to control the heat output of one or more internal combustion heaters.

Another object of my invention is to provide a new and improved heater system which will effectively and automatically control the heat output of an internal combustion heater lunder all operating conditions.

Another object of my invention is to provide a new and improved heater system which is specially adapted for use on aircraft and which will eiectively heat the aircraft cabin -or other space or spaces lunder all operating conditions.

Other objects and advantages will become apparent as the description proceeds.

In the drawings:

Fig. 1 is a diagrammatic view of a heater system embodying my invention;

Fig. la diagrammatically illustrates a modiiication which may be -incorporated in the device of Fig. 1.

Fig. 2 is a view showing a preferred installation of my heater system in an airplane; and

Fig. 3 is la detailed, sectional View of the fuel control valves taken on the line 3-3 of Fig. 1.

The installation shown in Figs. 1 and 2 comprises a pair of internal combustion heaters l and I2 mounted respectively in Ventilating air ducts i4 and I6 to heat air supplied to these ducts by rams i8 and 20 located outside of the fuselage of the airplane and directed forwardly so thaty operation of the plane forces air intoV these rams. Each of these Ventilating air ducts may have one or more outlets discharging heated Ventilating air into a single cabin or plurality of cabins or other spaces to be heated and the Viour outlets shown in the drawings for each of these ducts are to rbe considered as illustrative only;

The heater -Ill is supplied with a combustible mixture of fuel .and air by means of a iuel supply pipe 22 connected with a supercharger for oneof the plane engines 24. The fuel supplied to the combustion chamber of the heater l0 is ignited by an electrical igniter 26 which is grounded as indicated at 28 and which is supplied with current from any suitable source, such as a battery 38 which is grounded at 82. The igniter 26 is connected with the battery, 3U by a manually operated master switch 34, wires 36 and 36 and the usual thermostatic switch 40 which is aiiixed to the heater I0 and breaks the igniter circuit when the heater attains normal operating temperature. The hot products 'oi combustion give up their heat to the usual heat exchanger (not shown) and are illustrated as being discharged to atmosphere through an exhaust pipe 42 passing through the cabin wall 44 and discharging toward the tail of the airplane so that operation of the plane tends to create a suction in this exhaust pipe. n

. The fuel supply for the heater lll is controlled by a solenoid operated shut-o valve 46 and a solenoid operated bleed valve 48 located in the fuel supply line 22. The shut-off valve 46 is in a circuit including fthe battery 30, master switch 34, wires 38 and 38 and overheat switches 50 and 52. The switches 5ll'and 52 are normally closed when master switch 34 is closed and serve to hold the shut-oft' valve 46 in open position. The overheat switch 50 is a thermostatic switch which opens when 'the temperature of the ventilating air which has passed over the heater reaches an abnormally high temperature, such, for example, as 225. The overheat switch 52 is the usual thermostatic switch attached to the heater itselfY and opening only when this heater reaches an abnormally high temperature.

The bleed valve 48 is connected to the battery 34 through master switch 34, wire 54, cabin thermostat 58, wires and 62, duct thermostat 64 and wire 66. The duct thermostat 84 is a thermostatic switch which is responsive to the temperat-ure of the heated Ventilating air as it leaves the heater Ill and is set to open at any pre-selected temperature, such for example as 212 F. When it is desired not to use the -cabin thermostat 58, a shunt switch 68 may be manually closed to short circuit this thermostat.

The shut-off valve 46 and bleed valve 48 are shown more clearly in Fig. `3. The shut-off valve 46 comprises a body 10 to which a cover 12 is attached by screws 14, or in any other suitable manner. 'I'he body provides a iiood inlet I6 and a flood outlet 'I8 between which is located a par tition 80. `The movable valve member comprises a ilexible diaphragm 82 attached to an annular flange 84 by screws 86 and having a movable disc-like portion 88 closes the circular inlet end of the outlet 18. The diaphragm l2 is biased toward closed position and is held in open postion by a solenoid 92 having an amature 84 attached to the disc-like portion Il oi the tlexible diaphragm.

The bleed valve 48 is identical with the shut-of! valve 46, except that a restricted passage 88 is drilled in thepartition 80 so that when the diaphragm is in the closed position shown in Fig. 3 the supply of combustible mixture passing to the heater is limited to the amount which can flow through the restricted passage 86 which may be made of any suitable size to give anyfdesired operating characteristic. Since the bleed valve is otherwise identical with the shut-oi! valve, similar parts of the two valves bear identical reference characters. Solenoid shut-off valves like valve 46 are available on the open market and the bleed valve 48 can be easily made from such standard shut-oil valve by simply drilling the passage 86 without disassembling the valve as received from the manufacturer.

The cabin thermostat 50 is preferably ot the Fenwall type since this type of switch is particularly sensitive to slight variations .in temperature and may be readily'adiusted to maintain the cabin at any desired temperature, such, for

example, as 65 F. The word Fenwall is the.

trade name of a commercial type oi' thermostatic switch wherein the contacts are mounted on.bow shaped springs located inside ci and extending lengthwise ofl a metal sleeve whose longitudinal expansion and contraction -with ltemperature changes engages or disengages the contacts. This cabin thermostat is illustrated as being mounted in a tube 98 attached to and passing through a wall of the airplane cabin and communicating with an outlet |00 so formed that operation of the plane causes air to be drawn from thecabin through the tube 98 and discharged to atmosphere through outlet |00. '.This arrangement causes a constant ow of cabinair overthe thermostat 58 and results in this thermostat responding immediately to changes in air temperature in the cabin.

The heater I2 is identical with the heater I0 and has an igniter |02 for igniting the combustible mixture supplied to this heater throughic'a fuel supply pipe |04 which may be connected to the same engine supercharger as thefuel supply pipe 22 or to a diierent engine supercharger or other suitable source of combustible mixture.

This fuel supply pipe |04 is provided with a shutci valve |06 and bleed valve |06 which maybe,

respectively, identical with the shut-oiivalve46 and bleed valve 48 previously described.

The igniter |02 is connected to thebattery30 by way of master switch 34, `wires, 36 and ||0 and a thermostatic switch I|2 which cpensjwhen the heater attains normal operating temperature. The shut-off valve |06 is connected to the battery 30 by master switch 34 wires 36 and ||0 and overheat switches ||4 and ||6 which may be respectively identical with the `overheat switches and 52 previously described. The bleed valve |08 is connected with the battery. t0 through master switch 34, wire 54, cabin thermostat 58, wires and H0, duct thermostat |20 and wire |22. The duct thermostat |20 could be set to open at the same temperature as theduct thermostat 64 of heater i0.

Heater |2 is providedwith the usual heat exchanger (not shown) Vand communicates with an exhaust pipe |24 through which products of combustion formed in the heater are discharged |38 connected to the-damper |32.

to atmosphere. In lieu oi having the exhaust pipes 42 and |24 lead directly to atmosphere, they may lead into the supercharger inlets or may connect to a valve mechanism like that shown in my Patent No. 2,400,509, issued May 21, 1946, for selectively discharging these products of combustion either to atmosphere or to a supercharger inlet, depending upon whichever is most desirable for a particular operating condition.

In Fig. 2, I have illustrated my invention as being applied to a military type of Iplane in which all ci the heated Ventilating air is discharged into a single cabin |26 and each of the ventilating air ducts |4 and |6 is illustrated as being provvided with four outlets located in this cabin, although it will, of course, be understood that the number and arrangement of outlets may be varied as desired. Where all of the outlets are located in the same cabin, it is usually suilicient to provide each outlet with a manually controlled damper, as indicated by reference character |28 in Figs. 1 and 2. In commercial planes, however,

it is customary to divide the available cabin space into a plurality of separate or semi-independent rooms or sections and under these conditions it may be advisable to provide one or more of the Ventilating air outlets with an independent thermostatic control automatically to regulate the Ventilating air discharged through such outlet in accordance with the temperature conditions existing in the particular room or section into which this outlet discharges.

In Figs. 1 and 2, I have indicated such automatically controlled outlets by reference character |30. Each outlet |30 is provided with a damper |32 whose position is determined by a small proportioning motor |34 under the control of a room or section thermostat |36, the motors being preferably supplied with current from the battery or other current source 30 by way of the master switch 34 and wires 36 and |38. 'Ihese control motors are standard articles of commerce, one type being supplied by the Barber-Colman Company of Rockford, Illinois, so that a brief description of the operation of these controllers will suilice.'

In general, the mode of operation of these controllers or control motors is such that they automatically continuously cause the valve or damper to which they are connected to assume a desired position so as to maintain constant some certain temperature or barometric pressure. As an example, the motor |34 is of the series wound type and is connected to drive through speed reduction gearing and output shaft The output shaft is also connected to the swinging arm |40 of a variable resistor, the arm at its free end contacting a resistance coil |42. One of the motor armature brushes is connected to wire |38 and this wire is also connected to the swinging arm |40.' The other armature brush is connected to the center of a split field, the two field coils being indicated by reference characters |44 The above described portion of the controller comprises what is generally referred to as the receiving end of the circuit. of this circuit is attached to the wall of the room or section and comprises a thermostatic switch made up of a bi-metallic strip |48 which, at its free end, is equipped with upper and lower contacts |50 and |52. These contacts are so arranged that When the strip |46 iiexes upwardly the contact |50 will be brought against a sta- The sending end i 4attracts connected by wire |68 to the proper end of resistance element |42.

A-controller, asabove described, operates in the following manner. If the bi-metallic strip |48 is so positioned that an increasey in temperature will cause it to ex downwardly, such a tem' perature increase will bring contact |52 against contact |58 to establisha circuit from battery 30 through master switch 34 and wires 36 and |38 to arm |40 and one end of the motor armature. The circuit continues through the amature and field winding |46 and will cause the motor vto rotate in one direction.

At the same time this motor circuit is energized as above described, current will flow through resistor arm |40, a portion of resistance coil |42, through conductor |68 and solenoid |66, thus energizing the solenoid |66 which tends to move armature |64 upwardly and increase the tension of spring |52. As the motor continues to operate when connected in the manner above described, rotation of shaft |88 will move the damper |32' toward open position and will also move resistor arm |40in the same direction, thus decreasing the resistance of the variable resistor |42. 'I'his permits a greater current to flow has continued to operate for the proper length of time, the pull of solenoid |06 will overcome the temperature bias of the bi-metallic strip |48 and separate contacts |52 and |58.

The flexing of bimetallic strip |48 to separate contacts |52.and |58' will bring contact |50 into engagement with contact |54 to establish a xmotor `circuit through the other field coil |44 with the result that the motor rotates inthe opposite direction and moves the damper |32 toward closedpositlon y'while increasing the resistance of l the variable resistor |42. This reduction in resistance. v decreases the strength-of solenoid |66 andthe upward pull of the springl on the bimetallic strip |48. When the magnetic pull on thisstrip has been reduced some certain amount, the bimetallic stripl |48 will pull contact |50 away from contact. |54. The motor continually iluctuates in .its direction of movement -and thereby maintains the damper |32 lat approximately some predetermined position, depending on .the temperature l.of the air surrounding the strip |48, it being appreciated that a decrease in the temperature surrounding the bi-metallic stripwill cause this strip toexy downwardly` more strongly, thus requiring that a greater pro portion of the-resistor |42 be removed' from the circuit before the contact |52 will separate from understood, however, that these ground connec--f -tions can be eliminated and return wires or other suitable conductors substituted therefor.

Whenthe airplane is operating and the master 'l0 heat exchange means.

bleed valves of both heaters will be open and full ilow of combustible mixture will be supplied to the combustion chambers of the heaters where it will be ignited by the igniters 26 and |02. The

l hot products of combustion formed in the combustion chambers will pass through the heat-ex- (change means of the heaters and give up its heat to Ventilating air which enters rams I8 and 20 and flows throughA ducts I4 and |6 and over these The cooled products of combustion are discharged through exhaust pipes 42 and |24 to atmosphere in the particular embodiment shown in the drawings.

As soon as the heaters attain normal operating temperature, thermostatic switches 40 and I|2 opento disconnect the igniters 26 and |02 from battery 30, since ,the heaters, in, accordance with usual practice, are so constructed that they maintain combustion without these igniters go after the heaters have attained normal operat ing temperatures. Assuming that thedampers in the several outlets of the ducts I4 and I8 are open, the heated Ventilating air flows through these outlets and into the cabin |26.

The continuous discharge of a'smallamount ture for which this thermostat is set, the contacts of the. thermostat will separate, thereby breaking the circuit to the bleed valves 48 and` |08 andreducing the supply of combustible mixture to the heaters I0 and I2. Thereafter the heaters |0y and I2 continue to operate at reduced output through the solenoid |66 and increases the upper pull on bi-metallic strip |48. After` the motor f operation.

While under some conditions of operation the cabinthermostat 58 may control the bleed valves 48 and |08, under most operating conditions the opening and closing of these bleed valves will be regulated by the duct thermostats 64 and |20.

Preferably the ventilatingair passing over the heaters I0 and I2 is heated to a uniformvtempera-L turesuch, for example, as 212 F. under all conditions of operation and is supplied at this tem- 5'0 perature to the cabin or other spaces to be heated. `'The temperatureof thisheated ventilating air is preferably so selected that a 'person close to one of the outlets of the ducts I4 and I6 will not receive a, blast of extremely hot air and the heating system is so designed that its capacity for heating 'and ventilatingair to this temperature is sufficient to satisfy the maximum.

heat requirements of the cabin or other space to be heated and Where the heat requirements of thecabin or other space or spaces are less than maximum, the damper-s |28 and |32 are posi-` tioned to reduce the ow of Ventilating air into the cabin or other space.

In order to maintain the temperature of the 5 heated Ventilating air at almost exactly 212,

the duct thermostats 84 and |20 are preferably of the Fenwall type to afford the desired nicety of temperature control. Under normal operating conditions, the dampers |28 and |32 will restrict the. flow of Ventilating air over the heaters to such an extent that full operation of these heaters heats this ventilating air higherthan `212'2' As soon asthis occurs, ductswitches 64 and |20 open, whereupon bleed valves 48 and |08 close switch 34 is first closed, theshut-oi! valves and 75 and reduce the supply of combustible mixture to the heaters I and l2. This greatlyreduces the heat output of these heaters and after a period of time the temperature of the Ventilating air leaving these heaters drops below 212, 'whereupon duct switches 64 and |20 close and full `heater operation is resumed.

The periods between successive full heater op-- .erations will vary, depending upon the temperature ofthe atmospheric air supplied by the rams l0 and 20 'and also with the Volume of this air I passing over the heaters. When the atmospheric air is relatively warm and the heat requirements of the cabin relatively small, the dalnpers |28 and |32 will be almost closed and little air will iiow over the heaters. Under these conditions, the heaters will operate-for relatively long periods -of time on reduced fuel supply and for relatively short periods of time on full fuel supply. On the 'any person can open or close his particularoutlet to any desired extent Without interfering with the heatsupplied through the other outlets. The duct thermostats 64 and |20 maintain the heated Ventilating air at substantially` 2.12s for all rates of Ventilating air-flow and the temperature of the Ventilating air' supplied through one outlet is not aiected by opening or closing the other outlets. `Whenever the'control exercised by the cabin thermostat is not desired this control can be eliminated by closing the shunt switch 68. When this switch is closed, the heat output of the heaters is controlled entirely by duct thermostats 64 and |20 under normal operating conditions.

If all of the dampers '|28 and |32 are closed so that there' is very little ilowof Ventilating air over the heaters, the temperature of this Ventilating air will soon reach 212 and open duct switches 04 and |20. 'I'his will close bleed Valves 48 and |00 and reduce the fuel supply to the heaters.

Even this reduced fuel supply may produce heat sumciently to open one orboth of the overheat switches associated with each heater for controlling its shut-oil' valve and as soon as these -enough again to open the overheat switches and by the rams i8 and 20. so that no means need be provided to regulate the volume of air supplied by these rams.

The one exception occurs when the airplane is operating at slow speed and high altitudes where the atmospheric air is extremely cold. Under these conditions, the cabin requires a maximum amount of heat,A but the volume of air passing over the heaters is reduced by the decreased density of the atmospheric air. The decreased flow of Ventilating air over the heaters may be insumcient to absorb the full heat output of the heaters without rising to a temperature above 212 and thereby opening the duct switches 84 and |20 and reducing the fuel supply to the heaters. In order to meet this particular condition, the ducts i4 and I6 are provided with dampers |12 which may norshut down the heaters.` Such intermittent operation of the heaters will continue as long as the main switch remains closed and the dampers unduly restrict the flow of Ventilating air over the heaters.

From the foregoing, it will be apparent that the heater system thus far described has a wide flexibility of operation to heat the requirements of widely different operating conditions; The mass and temperature of the Ventilating air supplied to the heaters by the rams I8 and 20 will vary with the speed of the airplane and the temperature of the atmosphere through which l. if traveling. Under -almost all conditions of airpiane operation, the heating system which I have thus -far described is capable of meeting the heat requirements of the airplane cabin or other space, irrespective of the variations in mass and temperature of the Ventilating air supplied mally remain in fixed position wherein they prevent the rams I8 and 20 from supplying maximum air to the heaters. Only when the airplane is operating slowly at extremely high altitudes and in extremely cold atmospherel is it necessary to shift these dampers and then these dampers should be shifted to fully open position to permit maximum flow of air to the heaters l0 and l2. Since these dampers |10 and |12 may remain in partially closed position except under special operating conditions which are rarely encountered,

it is suilicient to provide a manual control for The damper |12 is illustrated as having a suit- A able manual control comprising an arm |14 attached to the damper shaft |16 and an operating link |18 pivoted to the free end of the arm |14. 'I'he operating link |18 may be provided with any of the usual hand1'es,buttons, or other suitable manual controls. The damper |10 of Fig. 1a, however, is illustrated as being provided with an automatic control which may be substituted for the manual control of Fig. l.

The damper |10 is operated b'y mechanism which is responsive to variations in temperature and altitude. This mechanism comprises a housing enclosingan-annular bellows |82 which comprises an outer bellowsmember and an inner bellows member which are attached to the end plate |84 of the housing |90 at one of their ends and to a movable disc at their opposite ends. 'I'he space between the outer and inner bellows members is evacuated and fluid pressure in the housing |80 tends to move the dis'c |86 attached to the bellows |82 toward the end plate |84. A spring |88 is interposed between the disc |86 and end plate |64 and tends to expand the bellows |82. Movement of the disc |86 shifts the position of the damper |10 through a rod |90 attached to the disc |86 and pivoted to an arm |92 aillxed to the damper shaft |94.

Part of the air entering-the rar'n i8 enters the inlet end |96 of a. Pitot tube connected by a pipe |98 to the housing |80 whereby the pressure of the air at the inlet end of this Pitot 'tube is communicated to the housing |80 and acts upon the bellows |82. The Pitot tube |96 has its inlet end swiveled so that its inlet end may point directly forward or at an angle, as shown in Fig. 1. A spirallyv wound bimtallic strip 200 has one end attached to a wall of the ram I8 and another end attached to the swiveled portion of the Pitot tube |96 whereby the angular position, of the inlet end of the Pltot tube Varies with the temperature.

The pressure in housing |80, therefore. varies with the temperature and' mass of air supplied to the heater l0 and acts to open the damper |10 While I have illustrated and described a heater system which is especially designed and particularly adapted for'use on airplanes and other aircraft, this heater system is not necessarily limited to such use, but may be applied to other purposes. This heater system is an improvement on the heating apparatus described and claimed in my co-pending application, Serial No. 452,714, filed July 29, 1942. While i'n the instant application I have shown and described only a single embodiment of my invention. 'it is to be understood that my invention is not limited to the particular details shown, but may assume numerous other forms and that the scope of my invention is delined in the following claims.

1. In an aircraft heating and. Ventilating system of the type in which ventilating air is collected by a scoop or ram projecting into the air stream and in which the air` thus collected is passed to the cabin by a duct and in which a liquid fuel'bur'ningheater having fuel supply means is arranged to heat the air passing through said duct; a control system comprising valve means for regulating the rate of heat output of said heater by regulating the rate of fuel ow through said fuel supply means, thermostatic means sensitive to the duct temperature downstream. of said heater for controlling said valve means, said thermostatic means being set to a temperature lower than that normally attainable by said heater when operating at full heat output so that' regardless of ram pressure conditions, ambient air temperature conditions or atmospheric pressure -conditions, the duct air temperature downstream of said heater remains substantially constant, and separate thermostatic means sensitive to thecabin temperature for controlling said valve means, the last said thermostatic means being adapted to override the nrst said thermostatic means to reduce the temperature oi the duct air downstream of said heater whenever the temperature in said cabin rises above a predetermined level and to return control of said duct temperature to the first said thermostat whenever the cabin temperature falls below substantially the same level, and damper means in said duct for regulating the pressure drop therethrough, said damper being arranged in partially closed position for low altitude operation, and means responsive to the mass rate o! air flow through said duct for controlling said damper, the last said means being adapted to shift said damper so as to lower the pressure drop through said duct whenever the ilow rate through said system drops below a predetermined level.

2. In an aircraft heating and ventilatlng system l of the type in which ventilating air is collected l by a scoop or ram projecting into the air stream and in which the air thus collected is passed to the cabin'by a duct and in which al liquid fuel burning heater having fuel supply means lis arranged to heat the air passing through said duct: a control system comprising valve means for regulatingthe rate o! heat output o! said heater by regulating the rate of iuel now through'said fuel supply means, thermostatic means sensitive to the duct temperature downstream of said heater for controlling said valve means, said thermostatic' means being set to a temperature lower than that normally attainable by said heater when operating at full heat output so that regardless of ram pressure conditions, ambient air temperature conditions or atmospheric pressure conditions, the duct air temperature downstream of said heater remains substantially constant, and separate thermostatic means sensitive to the cabin temperature for controlling said valve means, the last said thermostatie means being adapted to override the1iirst said thermostatie means to reduce the temperature of the duct 'air downstream of said heater whenever the temperature in said cabin rises above a predetermined level and to return control of said duct temperature to th'e "first said thermostat whenever'the cabin temperature falls below substantially the same level, and

damper means in said duct for regulating the pres" sure drop therethrough, said damper being arranged in partially closed position for low altitude operation, and means responsive to the mass rate of air iiow through said duct for controlling said damper, the ylast said means being adapted to shift said damper so as to lower the pressure drop through said duct whenever the iiow rate through said system drops below a predetermined level, and the last said means including temperature reature for tending to shift said damper to increase the pressure drop through said system whenever the ambient air temperature drops below a predetermined minimum.

SEYMOUR E. l REFERENCES CITED `The following references are of record in the le of this patent:

UNITED STATES PA Number Name Date 1,004,074 Powers 1.---..- Sept. 26, 1911 2,314,089 Hess et al Mar. 16, 1943 2,092,655 Page Sept. 7, 1937 1,566,854 Gold et al. Dec. 22, 1925 2,155,371 Anderegg et al Apr. 18, 1939 2,189,895 Grutzner Feb. 13, 1940 2,327,202 McCollum Aug. 17, 1943 2,009,823 Van Vulpin July '30, 1935 2,271,120 Grant Jan. 27, 1942 2,292,830 Ganger et al Aug. 11, 1942 2,308,887 McCollum Jan. 19, 1943 2,193,141 Price Mar. l2, 1940 2,266,563 McCorkle Dec. 16, 1941 2,259,061 Caiiier Oct. 14,' 1941 2,367,162 Whempner Jan. 9, 1945 2,364,458 McCollum Dec. 5, 1944 2,330,298 McCollum Sept. 28, 1943 2,290,066 Nessell July 14, 1942 2,235,620 Nessell Mar. 18, 1941 2,067,426 Stuart Jan. 12, 1937 2,160,740 Hutchins May 30, 1939 2,022,879 Carlberg Dec. 3, 1935 2,109,862 Kiechbaum= Mar. 1, 1933 2,188,775 Locke Jan. 30, 1940 2,403,917 Gille July 16, 1946 2,244,555 Harris Julie 3, 1941 Certificate of Correction Patent N o. 2,428,078. September 30, 1947.

SEYMOUR E. HEYMANN It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 2, line 53, strike out the Words closes the circular inlet end and insert instead adapted to move from the; line 55, for portion 8 read portion 88; and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the case in the Patent Oce.

Signedfand sealed this 6th day of April, A. D. 1948.

[SEAL] THOMAS F. MURPHY,

Assistant Qommz'ssiozter of Patents. 

